The long-term goal of our research is to understand how the brain controls and monitors the actions it produces. The activity of ensembles of neurons will be monitored in monkeys performing countermanding (stopping) tasks. Experiments will manipulate the properties and context of the stop signal. The frontal eye field will be studied to further elucidate the neural activity that species whether and when a movement will occur. The supplementary eye field and anterior cingulate cortex will be studied to characterize the neural concomitants of supervisory control signals. Patterns of ensemble neural activity will be analyzed to evaluate specific hypothesis about how the brain prepares and initiates movements (Aim 1), monitors the consequences of movements (Aim 2) and generates supervisory control signals (Aim 3). Understanding how the brain control normal action in necessary to understand the causes of dyscontrol underlying various psychopathologies.